Many conventional aqueous systems, such as industrial cooling water systems and others, have used treatment products to control undesirable fouling, such as scaling, corrosion, and microbiological growth. The fouling control materials have been used, for example, to control formation of scale or other fouling materials on substrate surfaces in contact with the water in the system. The fouling control materials also have been used, for example, to control the presence of the fouling material suspended in the water. Fouling control materials have included inorganic and organic materials. Polymers, for example, have been used to control scale and other fouling materials in aqueous systems. A treatment polymer added to water of an aqueous system can be consumed for one or more various reasons, for example, it may be consumed as it performs a desired function to control a fouling material, or be lost in blowdown of a cooling system, or for other reasons. Monitoring of the concentration of a treatment polymer in the water of the water system and replacement of lost amounts of treatment polymer has been done to maintain fouling control.
Various analytical methods have been used to measure the amount of the treatment polymer added to the water in industrial water systems. Inert (i.e., non-treating) fluorescent tracer compounds and methods of using them have been shown, for example, in U.S. Pat. Nos. 4,783,314; 4,992,380; and 5,171,450. Other fouling control agents that have been used in industrial water systems are polymers tagged with a fluorescent repeating unit or monomer. As shown, for example, in U.S. Pat. No. 5,986,030, a concentration of a treatment polymer has been determined using a fluorometer to measure the fluorescent signal of a fluorescent repeating unit or monomer thereof. Tagged polymers which incorporate chemically-synthesized quaternary salt fluorescent monomers are shown, for example, in U.S. Pat. Nos. 7,179,384 B2 and 7,875,720 B2. Some prior tagged polymers have required chemical synthesis of both the fluorescent monomers and the polymers incorporating these constituents. Additional cost and production complexity can occur if synthetic monomers must be manufactured before they can be incorporated into tagged polymers.
The present investigators have recognized that it is desirable to have a method of controlling the growth of scale or other fouling materials in aqueous systems which can use tagged polymers, which can be more easily obtained without need of extensive chemical syntheses, and/or which tagged polymers can be accurately detected and monitored in an aqueous system at relatively low concentrations, which are compatible with other water treating agents, and which are environmentally-friendly. The present investigators also have recognized a need to address background noise and interference which can affect the accuracy and consistency of spectrophotometric or spectrofluorometric monitoring and dosing of water treatment materials into the aqueous system under treatment.